Pumped Liquid Cooling

Pumped liquid cooling has been used in numerous applications including automotive engine cooling, avionics thermal control and nuclear reactor cooling. A typical pumped liquid cooling loop consists of a pump, a cold plate, a heat exchanger/sink and liquid lines. In many cases, reservoirs and valves are used to control the fluid volume and flow rate. The pump circulates the fluid in the loop, which picks up the heat in the cold plate and dissipates the heat through the heat exchanger.

Compared to capillary driven (passive) two-phase devices such as heat pipes, loop heat pipes and capillary pumped loops, pumped liquid loops provide more robust operation. Compared to pumped two-phase loops, pumped liquid loops are inherently simpler and more reliable.
Traditional channel flow cold plates have limited heat flux capability. Porous media and micro channels have been used to improve the cold plates’ heat flux capability up to hundreds to thousands watts per cm2.

However, these cold plates require large pumping power and the system pressures are typically on the order of tens to hundreds of psi. This presents significant difficulties in designing a pump that can operate reliably for many years in such a high pressure and high lifting environment. For microchannel cold plates, flow imbalance among the parallel channels is often a problem that can potentially cause temperature non-uniformity.

ACT has been developing advanced liquid cooling technologies that are capable of addressing the issues with conventional liquid cooling technologies. The goal of our efforts is to advance the liquid cooling technologies to being able to cool very high heat fluxes with minimal pressure drop penalty. In particular, ACT’s R&D efforts in this area have been on the following advanced technologies for a diverse range of applications, including cooling of power electronics and computer microprocessors.